Secretary of State John Kerry delivers a speech in support of the Iran nuclear deal in Philadelphia on Wednesday. 'Rejecting this agreement would not be sending a signal of resolve to Iran, it would be broadcasting a message so puzzling that most people across the globe would find it impossible to comprehend,' Kerry told lawmakers and civil leaders at the National Constitution Center.

Washington — With votes assured for a presidential victory in a veto fight over the Iran nuclear deal, the White House is now hoping for enough support to block opposition to the deal in the Senate – making sure that President Obama never has to take out his veto pen in the first place.

The thinking is this: If Congress were to pass a resolution of disapproval, it would weaken Mr. Obama in the eyes of the world. True, he would veto it, and this week he won enough votes to sustain that veto. But that very process would reveal a president barely able to get his way and would put the reliability of his handshake on international agreements in doubt.

“There’s a concern – I’m not sure how valid it is – that the administration would look weakened in the eyes of some of our adversaries if he had to enact this deal over the objection of Republicans in both the House and the Senate,” says Jim Manley, former spokesman for Harry Reid (D) of Nevada, the Senate minority leader.

There's also the issue of timing. Going through the veto process would leave the issue unresolved by the time of the UN General Assembly meeting later this month and possibly get in the way of coming up with an agreement to fund the federal government, which runs out of money on Oct. 1.

For months, the Democratic strategy has been to deny Republicans a veto-proof majority, if the GOP-controlled Congress passes a resolution to oppose the Iran nuclear deal. Sustaining a presidential veto would require only 34 Senate votes. Democrats hit that target on Wednesday.

Suddenly, the larger goal of blocking a vote on the deal altogether appears to be in reach.

Last month, Senator Reid said he hoped to stop the resolution of disapproval, which the Senate will begin debating next week, from “procedurally … moving forward.”

As of Friday morning, Senator Reid was only three votes shy of the 41 needed to filibuster or block the resolution. Just three Democrats – Chuck Schumer of New York, Bob Menendez of New Jersey, and Ben Cardin of Maryland, the top Democrat on the Senate Foreign Relations Committee – have broken ranks to side with Republicans, with five Democrats yet to declare.

But some Republicans are crying foul over Reid’s strategy. They consider the issue a matter of national security that is too important to subject to procedural maneuvering.

“This is not your typical debate,” Senate majority leader Mitch McConnell (R) of Kentucky said at a press conference in early August. “We intend to handle this issue with dignity and respect,” he said. When senators begin debating the issue on Tuesday, leader McConnell has asked senators to all be at their desks for the debate – a rarity.

Beyond that, though, would be the hypocrisy of bottling up a vote that both parties worked hard to get, say some lawmakers on both sides of the aisle. It took a huge bipartisan effort to craft and pass the Iran Nuclear Agreement Review Act earlier this year – legislation that gave Congress the ability to scrutinize the agreement and vote up or down on it. In the end, the Senate approved the review act by a vote of 98 to 1.

“All but one senator voted in favor of having the right to vote on the final deal, so then to turn right around and filibuster it to me is very inconsistent and I think would be confusing to the people they represent,” Sen. Bob Corker (R) of Tennessee, told the Associated Press last month. He called Reid’s comments “stunning.” Senator Corker is the chairman of the Senate Foreign Relations Committee that produced the review act.

But Republicans are voicing some “serious faux outrage” about a filibuster, according to Ben Marter, spokesman for Democratic minority whip Dick Durbin of Illinois. Debate is going to begin on the bill and there will be votes, Mr. Marter said in an e-mail.

Moreover, 60 votes is now the common threshold to pass any piece of major legislation in the modern Senate, he said.

“After Republicans have done everything they can to grind the place to a halt with one filibuster after another during the Obama administration, the idea that they’re complaining now is ridiculous,” said Mr. Manley. Most Republican senators, he points out, opposed the deal before its details were even announced.

But other Democrats agree that the issue of sufficient importance that the deal should not be filibustered.

“Senate Democrats agree that the American people deserve a full and open debate and that Congress deserves to vote on the critical need to stop Iran’s nuclear weapons program,” Marter said.

On CNN this week, Sen. Chris Coons (D) of Delaware – who supports the deal – said it would be “regrettable if we didn't ultimately go to the floor and cast our votes for or against this deal.”